With only being able to carry one AVG versus carrying three C4s, taking the C4s is still better. Currently it takes 2 C4s to take out a lightning, and 3 C4s to destroy a MBT or Sunderer.
Suit Modification: Munitions Pouch.
As the only class that can carry/use the rocket launcher, having the max number allowed rockets will only help your cause. Especially helpful if there are no engineers around to drop you an ammo pack.
On average it takes about five rockets to take out a vehicle when hitting it from the front without reinforced armor. So try to wait before revealing your position, and try to hit vehicles from the rear.